Anode purge gas dilution

Abstract

A system includes a fuel cell that has an anode chamber that is in a deadheaded configuration. A controller of the system controls a valve that is connected to the anode chamber pursuant to a modulation scheme to purge the anode chamber.

1 . A system comprising: 
 a fuel cell having an anode chamber in a deadheaded configuration;    a valve connected to the anode chamber, and    a controller to control the valve pursuant to a modulation scheme to purge the anode chamber.    
   
   
       2 . The system of  claim 1 , wherein the modulation scheme comprises a pulse width modulation scheme.  
   
   
       3 . The system of  claim 1 , further comprising: 
 a flow restrictor connected to the valve to limit a rate at which a flow exits the purge valve.    
   
   
       4 . The system of  claim 1 , further comprising: 
 a dilution air source connected to dilute a flow that exits the purge valve.    
   
   
       5 . The system of  claim 1 , wherein the controller controls the valve to constant cycles pursuant to a pulse width modulation scheme, each cycle comprising a constant open time in which the purge valve is continuously open and a closed time in which the purge valve is closed.  
   
   
       6 . The system of  claim 1 , further comprising: 
 a dilution source to dilute a flow provided by the valve.    
   
   
       7 . The system of  claim 1 , further comprising: 
 a motor vehicle,    wherein the fuel cell, valve and controller are part of the vehicle.    
   
   
       8 . A system comprising: 
 a fuel cell having an anode chamber in a deadheaded configuration; and    a vessel downstream of the anode chamber to temporarily store a purge flow from the anode chamber and provide an exhaust flow to rid the vessel of the stored purge flow,    wherein the purge flow is stored in the vessel at a first rate that is substantially larger than a rate at which the purge flow leaves the vessel.    
   
   
       9 . The system of  claim 8 , further comprising: 
 a valve; and    a controller to intermittingly open the valve to communicate the purge flow from the anode chamber to the vessel.    
   
   
       10 . The system of  claim 8 , further comprising: 
 a flow restrictor connected to an outlet of the vessel to limit a rate at which a flow exits the vessel.    
   
   
       11 . The system of  claim 8 , further comprising: 
 a dilution air source connected to dilute the exhaust flow that exits the vessel.    
   
   
       12 . The system of  claim 8 , further comprising: 
 a motor vehicle,    wherein the fuel cell and the vessel are part of the vehicle.    
   
   
       13 . A system comprising: 
 a fuel cell having an anode chamber in a deadheaded configuration and adapted to provide a cathode exhaust flow;    a mixer to dilute a purge flow from the anode chamber with the cathode exhaust flow to provide a diluted flow; and    a dilution source to further dilute the diluted flow.    
   
   
       14 . The system of  claim 13 , wherein the dilution source comprises an air source.  
   
   
       15 . The system of  claim 13 , further comprising: 
 a motor vehicle, wherein the fuel cell, the mixer and the dilution source are part of the vehicle.    
   
   
       16 . The system of  claim 13 , further comprising: 
 a valve to regulate communication of the purge flow from the anode chamber; and    a controller adapted to: 
 increase the cathode exhaust flow from a first rate to a higher second rate;  
 after the increase, cause the valve to open to communicate the purge flow from the anode chamber;  
 close the valve; and  
 after closing the valve, return the cathode exhaust flow to the first rate.  
   
   
   
       17 . The system of  claim 16 , wherein the controller is further adapted to maintain the valve open and maintain the cathode exhaust flow at the second rate until a concentration of fuel is detected below a minimum threshold.  
   
   
       18 . The system of  claim 13 , wherein the controller is further adapted to operate the valve pursuant to a pulse width modulation control scheme.  
   
   
       19 . The system of  claim 13 , further comprising: 
 a vessel located downstream of the anode chamber to temporarily store the purge flow.    
   
   
       20 . A method usable with a fuel cell, comprising: 
 configuring the fuel cell to be in a deadheaded configuration; and    controlling a valve pursuant to a modulation scheme to purge an anode of the fuel cell.    
   
   
       21 . The method of  claim 20 , wherein the modulation scheme comprises a pulse width modulation scheme.  
   
   
       22 . The method of  claim 20 , further comprising: 
 using a flow restrictor to limit a rate at which a flow exits the anode.    
   
   
       23 . The method of  claim 20 , further comprising: 
 providing a dilution source to dilute a flow provided by the valve.    
   
   
       24 . A method usable with a fuel cell, comprising: 
 configuring the fuel cell in a deadheaded configuration;    temporarily storing a purge flow from an anode of the fuel cell;    providing an exhaust flow to remove the storage; and    causing the rate at which the purge flow is stored to be substantially larger than a rate at which the stored purge flow is removed.    
   
   
       25 . The method of  claim 24 , further comprising: 
 intermittently opening a valve to communicate a purge flow from the anode of the fuel cell.    
   
   
       26 . The method of  claim 24 , further comprising: 
 limiting a rate at which the purge flow is removed from storage.    
   
   
       27 . The method of  claim 24 , further comprising: 
 diluting a flow that removes the purge flow from storage.    
   
   
       28 . A method usable with a fuel cell, comprising: 
 configuration the fuel cell in a deadheaded configuration;    diluting a purge flow from anode of the fuel cell with a cathode exhaust flow from the fuel cell; and    further using a source other than the cathode exhaust flow to further dilute the purge flow.    
   
   
       29 . The method of  claim 28 , wherein the act of further using a dilution source comprises using an air source.  
   
   
       30 . The method of  claim 28 , further comprising: 
 increasing the cathode exhaust flow;    after the increase of the cathode exhaust flow, purging the anode of the fuel cell; and    at the conclusion of the purging of the anode, reducing the cathode exhaust flow.